The Prevalence of Early Childhood Caries among 24 to 36 Months Old Children of Iran: Using the Novel ICDAS-II Method

Statement of the Problem Early childhood caries is an important oral health issue. Finding its prevalence would predict the need for oral health promotion disciplines for specific age groups. Purpose The aim of this study was to assess the caries experience of children living in Tehran, Iran. It also would evaluate the impact of gender, ethnicity, and socioeconomic status (SES) on this oral condition. Materials and Method This epidemiological cross-sectional study was based upon stratified cluster random sampling. The samples consisted of 239 children (2- to 3- years old) registered in Tehran’s public healthcare centers for “Healthy Child Program”. Mothers of the recruited children were interviewed for the background data; then children were examined for the oral health status according to ICDAS-II (International Caries Detection and Assessment System) and WHO (World Health Organization) criteria. Statistical analyses were conducted using STATA.11 for SES classification considering six socioeconomic variables, and SPSS.21 for descriptive/analytical analyses. Results Primary Component Analysis (PCA) demonstrated five classes of SES ranging from the lowest to the highest. The distribution of caries-free (CF) children was 10.87%, non-cavitated enamel caries (codes 01-02) were 28.03%, and about 61.1% had cavitated caries (codes 03-06). There was no significant difference in caries experience between the two genders. Cavitated lesions were more prevalent among Kurdish, who also had the least CF children. Caries prevalence, especially code 02, was more among children from 3rd class SES (moderate level). Gender, ethnicity, or SES had no impact on the CF status of the children; however, ethnicity showed significant impact on the prevalence of extensive caries (codes 05-06). Conclusion The result of the present study is indicative of high caries prevalence among 2 to 3 years old children residing in Tehran. It highlights the need for comprehensive oral health promotion disciplines for this age group.


Introduction
Dental caries remains the highly prevalent oral lesion. It is a worldwide issue and continues to be one of the pandemics among children regardless of the socio-economic status and how well developed a country is.
[1] Although caries is preventable, when developed it lives with the affected individual for life and constitutes economic and social burden. Once a restoration is placed, the tooth enters into a restorative cycle in which the several replacements would happen throughout the life. [2][3][4][5][6][7][8] Iran's National Oral Health Survey reported a prevalence of 47% dental caries among 3-year-old Iranian children in 1999 (dmft=1.8±0.02) (decayedmissing-filled-surfaces). The severity of the disease slightly increased along with its prevalence and reached 52% with dmft of 1.9 by 2004. [9][10] In 2005, Mohebbi and her associates reported that 3% to 33% of 1-to 3-year old children settled in Tehran experienced dental caries (mean dmft=1.1, CI=0.6-1.6). [11] These studies reported no significant relationship between level of education and occupation of parents with the rate of dmft. [10][11] Current epidemiological data available on dental caries status of Iranian children is mostly is based on "WHO Caries Assessment Criteria" (WHO-CAC) which records only the cavitated teeth. [5,7,12] In 2002, the "International Caries Detection and Assessment System" (ICDAS) was first introduced by an international team of caries researchers. [13] It was later more developed as ICDAS-II in 2005. [14] The major purpose was to integrate several newly added criteria systems into one standard system for caries detection and assessment as well as to improve its consistency. [15] This system is considered as an evidencebased clinical caries scoring system and can be integrated to dental education and clinical practice. The index can improve the quality of diagnosis of dental caries. It is also applicable in research methodology and epidemiology. Moreover, it is a public health tool for community-based oral health promotion plans. [13,16] The ICDAS has been applied in a number of epidemiological settings as well as clinical practice and researches. [17][18][19][20][21] It is well used by European Global Oral Health Indicator Development Program to make the comparison of information easier between all of the union members. [22] As well as other countries, the ICDAS-II criteria have been applied in two different domains of two national investigations in Iran, clinical research and education. [23] Finally, a comprehensive article has also pointed out the risk factors of tooth decay in primary dentition. [24] The present study discusses the community oral health implementation of ICDAS-II criteria in 2-to 3-year old Iranian children. This cross-sectional study presents caries experience of young children living in Tehran, the capital city of Iran. It also describes the pattern of dental caries development in this age group. Furthermore, it analyses the prevalence of this oral condition in relation to the ethnicity and the SES level of the participated children.

Materials and Method
Sampling and sample size The samples were selected of children registered in public healthcare centers participated in the oral health promotion plan for different SES and ethnicity groups.
This plan has the enrolment of nearly 85% of young children residing in Tehran. [25][26][27] [28] According to the ICDAS-II protocol, all tooth surfaces must be cleaned and freed of any dental plaque before oral examination. [29] The examination can be performed in either wet or dry conditions. Tooth surfaces are scored for both caries and restoration status leading to a two-digit number. The first digit represents the caries condition, while the second digit represents the restoration status. (Table 1) [7,29] When using ICDAS method, air-drying can be substituted with damping with cotton wool/gauze. It should be mentioned that ICDAS codes can also be calculated as d 3 mf values. [7] Stratified cluster random sampling was used as a proper method in this study. Participation in this investigation was fully voluntary. Districts of Tehran were stratified to three strata of North, Center, and Southregions. Then, three public health care centers were randomly selected in each stratum. Two hundred and thirty nine 24-to 36-month old children registered in According to PCA, participants of the study were categorized to five classes in which 0-20 represented the lowest, "1 st class", 21-40 the next, "2 nd class", 41-60, "3 rd class", 61-80: "4 th class" and 81-100 the highest, "5 th class". These classes were used in the following analysis of the study as "one factor" (SES).

Calibration of the Examiners
Two examiners were calibrated to screen child's teeth using two methods. One examiner was trained for WHO method and the other for ICDAS-II method. The Kappa agreement was calculated between the first examiner and the second examiner, a faculty member of restorative and cosmetic dentistry department of the dental school. The second examiner was trained by a standard assessor in cariology, who was an approved expert in ICDAS-II coding system. The training module was a three-month electronic course. Twenty patients were examined in two rounds, ten patients in each round.
Kappa coefficients analysis for validity and reliability of the first examiner was calculated.  accepted the procedure of this study through informed consent. All questions in the questionnaire were scored by specific codes. The data extracted from the completed questionnaires were entered into the software using the above codes.

Statistical Analysis
The data was analyzed using SPSS (Version.21) and STATA (Version.11). All data obtained from interview and oral examination were entered into SPSS and double checked with regard to the original questionnaire and examination forms to eliminate the data entry errors. The corrected version was confirmed using frequency analysis. In addition, to get a specific "single factor" for SES, the data was entered into the STATA Because of the presence of some common cultural characteristics between Kurdish, Lurs and Afghans, these ethnic groups were merged together and were classified as a three-level categorical predictor to implement regression analysis. In addition, by joining 1 st with 2 nd class as "low",3 rd as single class of "moderate", and 4 th with 5 th as "high", SES classes were redefined for effective analysis.
Binary logistic regression analysis was conducted to interpret the impact of three assumed predictors (gender, ethnicity, and SES) on the presence of dental caries among 2-to 3-year old children. This dichotomous dependent variable was described as caries-free (CF) and was allocated "zero" and "1" code to explain two conditions, absence or presence of caries, respectively. Multiple linear regression analysis was used to observe the impact of three categorical predictors on the frequency of ICDAS-II codes.

Results
In comparison with the standard examiners, Kappa coefficient analysis for validity of the first examiner was 0.7 for d 1  In addition, each participant experienced at least    There was no significant difference between other ethnic groups.
ANOVA analysis also showed that the mean difference of the frequency of code 00 and code 02 was     and 37.5% non-cavitated lesions) caries experience. [20] A recent study also stated a prevalence of 69.9% caries experience among 3-year-old children living in Medellin, Colombia. [19] Regarding the pattern of caries development among recruited children in the present study, the upper right quadrant of the child's mouth was the most opportunistic site to start and progress dental caries. The direction of the dental caries progress was from midline including interproximal surfaces of the central incisor teeth to the posterior sites of the child's mouth. The dental caries developed both in maxillary and mandibular teeth and involved labial and occlusal surfaces. It follows the progressive pattern as described by ADA for early childhood caries (ECC) detection. [31][32]

Conclusion
Irrespective of the gender, ethnicity and SES, there is a high distribution of dental caries among young children which merits a priority attention for community oral health promotion. Building public health policies to promote oral health of children from birth is recommended. Impact of ethnicity as a predictor of the frequency of dentinal caries confirms that minorities are much more susceptible to the EEC condition. Implementing community healthcare programs for pregnant mothers and continuing primary care of infants after delivery is an invaluable service. [33]